1. Field of the Invention
The invention relates to a mechanical brake actuator providing an easy preventive measure for brake cable disengagement.
2. Description of the Related Art
A brake actuator of this type is comprised of a plate-like brake lever, a strut pivotally retained the brake lever therein, and a pivotal pin, wherein the mechanical actuator is positioned between a pair of brake shoes, and the brake lever and the strut relatively rotates as operating, i.e., pulling a brake cable connected to the brake lever, while spreading the brake lever and the strut apart from each other in an opposite direction.
After engaging the brake cable with the brake lever as inserting a connecting pin in a brake cable-connecting hole of the brake lever exposed out from an opening of the strut, a C-like bending clip attaches to an exterior of facing plates of the strut, and concaves formed on both inner surfaces of the clip engage with convexes formed on both outer surfaces of the strut to position the brake lever within the space of the strut via the clip. The basic structure of this brake actuator is disclosed in the paragraphs 0015-0016 and FIGS. 2-4 of the Japanese Provisional Patent Publication No. 2001-349360.
Instead of the above-described structure, the paragraphs 0020-0023 and FIGS. 5-8 of the same reference shows that the clip is assembled on the exterior of the facing plates of the strut as rotatably attaching to the strut.
Problems to be resolved by the invention are as follows:
(1) An independent clip is more complex in assembly and leaves a possibility of losing the clip and/or to neglect the clip assembling.
(2) If the clip is assembled on the strut, a rotational axis needs to be on both outer surfaces of the strut, which increases the manufacturing cost.
(3) Because of providing the convex and the rotational axis on the strut, high accuracy in the formation of the projection and the rotational axis (i.e., coaxially) is necessary, which requires higher manufacturing accuracy.
(4) At least, the clip plate thickness becomes easily interfering with nearby parts such as a shoe return spring adjacent to the strut.
Therefore, operability as attaching the clip to the strut is jeopardized, and there is a possibility of nearby parts being obstacles, which prevents the clip from attaching to the strut.
(5) The clip needs to be widened so as to attach to the exterior of the strut. Thus, a material cost of the clip increases, and a manufacturing cost of the clip increases due to the necessary high accuracy of providing the concave and the rotational axis in the clip (i.e., coaxially).(6) For the independent clip, when attaching the clip to the strut, side surfaces of the clip needs to be pushed out to spread open and maintained the condition by fingers until traveling over the convex of the strut, and the respective concave of the clip is arranged to fit on the convexes of both sides of the strut, which jeopardizes the operability of the clip attaching operation.
The invention was made in consideration of the above problems, and a main object of the invention is to provide the mechanical brake actuator realizing the miniaturization of the entire device and the reduction of the parts and manufacturing costs. Furthermore, another object of the invention is to provide the mechanical brake actuator remarkably improving the clip attaching operation.